Fixation of Ultrasound Transducers for Spinal Cord Neuromodulation in Mice
August 1st, 2025
This protocol describes an ultrasound transducer fixation system specifically designed for ultrasound stimulation of the spinal cord in awake mice. The method employs a fixation system to ensure accurate positioning of the ultrasound transducer while simultaneously allowing the experimental subjects to move freely without compromising the precision of stimulation.
Our research develops an implantable fixation system enabling precise ultrasound neuromodulation of the spinal cord in awake freely moving mice for chronic pain and spinal injury studies. Beyond spinal focused advances like microbial drug delivery, emerging brain spinal interfaces now combine ultrasound with neuro decoding to restore motor function after injury. Awake mice lacked stable spinal ultrasound fixation, our protocol closes this gap enabling painless, repeatable neuromodulation without anesthesia or displacement.
Our implant enables chronic precise spinal neuromodulation in awake mice, accelerating studies on pain circuits, spinal injury repair, and minimally invasive brain spine interfaces. To begin secure an anesthetized mouse using an adjustable stereotactic adapter. Use an electric clipper with a blade gap of 0.1 millimeter to remove the hair from the surgical site.
Palpate the last rib, which is attached to the T 13 vertebrae in mice, and use it as a landmark for incision positioning. Then using a scalpel, create a 2.5 centimeter incision at the T 13 vertebral level along the dorsal midline. Now use micro scissors to perform a sharp dissection of the paraspinal muscles to expose the vertebra.
Position a custom metal base bilaterally at the T 13 spinal transverse processes. Wear an eye shield and a mask during this procedure to ensure safety. Next, use a precision bone drill operating at 5, 000 to 10, 000 revolutions per minute to create a planar contact surface while irrigating with saline.
Attach the ultrasonic collimator and metal base to the vertebral column using cyanoacrylate adhesive mixture. When the adhesive has cured, separate the metal base from the plastic fixation rod. Then use 4.0 nylon sutures to perform interrupted suturing to close the incision.
The total distance traveled by mice in the open field test did not differ significantly between the preoperative and postoperative phases. Ultrasound energy at the focal spot attenuated by 39.94%after passing through the mouse vertebral lamina with maximum central pressures dropping from 746 kilopascals to 448 kilopascals. Cold plate testing showed that paw withdrawal latency was significantly reduced in the sham group compared to control, but restored to near control levels following low intensity pulsed ultrasound treatment in the LIPUS group.
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Overview
This study presents an implantable fixation system for accurate ultrasound neuromodulation of the spinal cord in awake, freely moving mice. The method aims to facilitate chronic pain and spinal injury research by enabling precise, painless neuromodulation without the need for anesthesia.
Key Study Components
Area of Science
- Neuroscience
- Neuroengineering
- Pain research
Background
- Traditional methods of spinal ultrasound fixation in awake mice lacked stability.
- The study enhances approaches to neuromodulation for chronic pain conditions.
- Potential applications include motor function restoration after spinal injuries.
Purpose of Study
- To develop a novel fixation system for accurate spinal ultrasound stimulation.
- To enable chronic and repeatable neuromodulation in awake mice.
- To accelerate research into pain circuits and spinal injury repair.
Methods Used
- The study involves ultrasound neuromodulation techniques in vivo.
- The biological model includes awake, freely moving mice subjected to spinal interventions.
- Key surgical steps include hair removal, incision at the T13 vertebra, and attachment of custom fixation components.
- Ultrasound energy measurements and behavioral assessments (e.g., open field test) were conducted pre-and post-operation.
Main Results
- The protocol successfully addresses prior limitations in spinal ultrasound fixation.
- Ultrasound energy attenuation and maximum pressure changes were measured.
- Paw withdrawal latency was significantly altered following treatment, indicating effective neuromodulation.
Conclusions
- This innovative protocol demonstrates a reliable method for spinal ultrasound stimulation in awake mice.
- It paves the way for advanced studies in chronic pain and spinal injury repair.
- The findings are significant for understanding the mechanisms underlying spinal neuromodulation.
